A jet ejector pump can be defined as a suction pump in which fluid under high pressure is forced through a nozzle into an abruptly larger tube where a high-velocity jet, at a low pressure in accordance with the Bernoulli law, entrains gas or liquid from a side tube opening just beyond the end of the nozzle to create suction.
Known in the art are ejector pumps of different types.
For example, U.S. Pat. No. 6,619,927 issued in 2003 to D. Becker, et al. describes an ejector pump provided in a fuel tank of a motor vehicle, which has a nozzle produced integrally with a mixing tube. The mixing tube is shaped in the form of a tubular cylinder, so that virtually the entire ejector pump may be produced from plastic in a mold allowing axial demolding. The nozzle is therefore aligned, exactly with respect to the mixing tube. The ejector pump consequently has a particularly high efficiency.
U.S. Pat. No. 6,394,760 issued in 2002 to P. Tell relates to a vacuum ejector pump. The ejector includes two or more nozzles arranged in series. A stream of air fed at high velocity through the nozzle is used to create a negative pressure in an outer, surrounding space. The surrounding space is in flow communication with at least one slot located between the nozzles. The nozzles are coupled together and assembled into an integrated nozzle body having at least one flexible valve member integrally arranged within the nozzle body to cover the flow communication with the surrounding space upon reaching a certain, desired pressure difference between the surrounding space and the atmosphere.
Russian Patent No. 2,247,873 issued in 2005 to A. Havkin, et al. relates to an ejector pump for delivery of various composite fluids to oil wells. The device comprises a housing, a union pipe connected to the housing which is used for the supply of the ejecting fluid, a union pipe for the fluid to be ejected, and a sleeve one part of the inner surface of which forms, in combination with the outer surface of the union pipe of the ejected fluid, an annular nozzle. This nozzle is connected to the pipe union of the ejecting fluid. The remaining part of the inner free annular space forms a mixing chamber, diffuser connected to the aforementioned chamber, and a pipe for discharge of the aforementioned mixture.
US Patent Application Publication No. 2005-2729 published in 2005 (inventor: S. Morishima) discloses an ejector pump which works to use dynamic energy of a jet of a main fluid emitted from a nozzle to suck a sub-fluid therein. When it is required to stop the ejector pump, the needle is moved to bring a sealing surface formed on a head thereof into abutment with a sealing surface formed around a main fluid flow path extending inside the ejector pump to close the main fluid flow path, thereby inhibiting the fluid pressure from acting on any downstream device. Upon the abutment, the needle is kept away from a nozzle, thereby avoiding undesirable wear or deformation of the needle and nozzle.
European Patent No. EP1378670 issued in 2004 to U. Engels describes a suction jet pump, which has an overflow beaker under its mixing tube. The mixing tube, complete with the diffuser on its outflow end, comes out into the beaker, which encloses it but is spaced out from it. It has an overflow aperture, which is fitted above the outflow end of the diffuser in the direction of flow.
Russian Patent No. RU2216651 issued in 2003 to S. Tsegel describes an installation for compression and delivery of different gaseous media to consumers. Proposed installation contains a pump, a separator and a liquid-gas jet apparatus. The pump is connected by its delivery side to an inlet of liquid into the liquid-gas jet apparatus, and by its suction side to the outlet of liquid medium from the separator. The liquid-gas jet apparatus is connected by gas inlet to a compressed gas source and by the gas-liquid mixture outlet to the separator. A branch pipe made on the housing of the separator in its upper part serves to let out compressed gas. Housing of the separator is partially filled with liquid medium. The separator is furnished with a drain chute, a set of phase separating nozzles and a louver pack. The drain chute is located along the separator housing. An inlet of the gas-liquid mixture in the separator from the liquid-gas jet apparatus is made over the inlet section of the drain chute. A set of phase separating nozzles is installed at the outlet of the drain chute, not higher that its outlet section. The louver pack is installed under the drain chute between the outlet of liquid medium from the separator and the set of phase-separating nozzles.
However, the ejector pumps described in the above references are designed for specific purposes, and none of them can be used as a universal pumping or suction machine for application in fields of industry for which it is not specifically designated.
It is known that existing centrifugal ejector pumps are characterized by simplicity of construction, high reliability of operation, (almost on the same level as that of a centrifugal pump that provides continuous supply of water to an ejector nozzle), and the highest volumetric/mass output capacity. However, the aforementioned existing centrifugal ejector pumps have low efficiency of energy use and are characterized by a limited field of applications (e.g., for evacuation and maintaining a reduced pressure in closed volumes).
A schematic view of a typical fluid-jet ejector nozzle is shown in FIG. 1. In fact, the pump shown in FIG. 1 is a generalized version of the pumps described in the aforementioned patent publications of the prior art, except that in some of the previously described publications the fluid to be ejected is a liquid and in some is gas.
Such a fluid-jet pump, which as a whole is designated by reference numeral 20, has a centrifugal pump unit 22, which is driven into rotation by a motor 24 for sucking air from the surrounding atmosphere. The air is delivered along a pipeline 26 to a diffuser 28 that has a narrowed cross-section portion 30 as compared to the pipeline 26. Existence of the narrowed cross-section portion 30 provides a reduced pressure in the area of the diffuser 28. This effect is used for intake of a fluid from the space around the diffuser 28. In the embodiment illustrated in FIG. 1, the aforementioned space is shown as a closed vacuum chamber 32. The fluid that fills the vacuum chamber 32 is drawn into an outlet pipe 34. For higher efficiency, the entrance into the outlet pipe 34 also may have a narrowed-section portion 36. In fact, the space between the exit from the pipeline 26 and the entrance into the pipe 34 comprises the aforementioned diffuser 28. In the above example, the air sucked by the pipeline 26 is an ejecting fluid and the fluid taken by the outlet pipe 34 is an ejected fluid.
In principle, and more often, the ejecting fluid used in the centrifugal pumps of the installations of the type described above, is a liquid, e.g., water, while the ejected fluid may comprise either a liquid or a gas.
An additional disadvantage of the pumps of the aforementioned type is inability of using thereof for compression of gases.
Furthermore, It should be noted that in a conventional ejector-type rotary machine the main source of all the losses is associated with movement of the working medium (which in most cases is liquid or gas) which is used as a carrier of energy for accomplishing the required work.